Worldwide axle/wheel manufacturers produce a diverse variety of railway wheel cross sections for rolling stock currently in service throughout North America. These diverse and varied wheel cross-sections present a significant challenge to any methodology or approach attempting to achieve reliable wheel defect detection.
Numerous examples of defective railway wheels have fragments of various size that have broken away from the wheel tread. Many of these defects are on the outermost edge (field side) of the wheel rim and are not detectable at Wheel Impact and Load Detection sites, commonly referred to as “WILD” sites. The detection of the majority of these defects would require monitoring the field side of each rail.
One of the most challenging aspects of the development of an accurate and reliable broken wheel detection system is the diverse variety of wheels currently in use on railroads throughout North America. Different cross-sections will require sophisticated approaches to ensure that specific locations on the wheel circumference, most susceptible to breakage, are accurately assessed to correctly detect wheel edge defects. Wheel design differences are further exacerbated by the significant age of some wheel designs still in use today. Combined with broad climatic condition operational requirements, dynamic vertical wheel movements typical during testing, elevated wheel speeds, and the requirement for accurate (virtually error free) detection presents a significant challenge for any wheel defect assessment system.
What is needed, therefore, is an accurate, reliable, robust and cost-effective broken wheel detection system that is capable of identifying rolling stock wheel defects continuously at full track speed for any type of wheels with no impact to traffic flows, for all wheels in each train consist.